The screenshots appeared to show an intimate relationship between Mr Kean and Ms Petinos, with the minister telling the MP that he was "tempted to drive down and see you".

Hornsby MP and Minister for Innovation Matt Kean pictured in a post uploaded to his Instagram page for Valentine's Day 2018.Credit:Instragam/Matt Kean

Ms Petinos then asks if Mr Kean misses her, to which he responds: "Yup, really need to f--- you."

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In her caption on the posts, Ms Keage said her boyfriend was another example of a "minister getting away with his predatory behaviour" and accused him of cheating on her while she was away with family.

Ms Keage promptly deleted the February posts but they spread rapidly through political circles. She subsequently went on leave and Fairfax Media has confirmed she is no longer employed in Mr Turnbull's office.

When the Instagram posts went public, Mr Kean issued a statement expressing regret that his relationship had "ended in such a spectacular and sad fashion".

NSW Premier Gladys Berejiklian said she was "personally disappointed" with Mr Kean, who is considered a promising talent in the Liberal Party, but insisted it was not relevant to his job performance.

Ms Keage, a South Australian, has worked in various staffing positions in federal politics since 2010.

There was speculation about her being the Liberal candidate for the electorate of Boothby at the 2016 election but that seat was successfully contested by Nicolle Flint.

Ms Keage's departure comes at a time of significant discussion around sexual relationships in politics, with the Prime Minister banning federal ministers from sex with staffers after former deputy prime minister Barnaby Joyce's affair was revealed.